Trezor has revealed that phishing attacks against its customers earlier this week targeted 347,000 email addresses and affected 2,500 users who clicked an embedded malicious link.
As Trezor warned on Wednesday, threat actors who breached Brevo, its third-party email provider, were emailing customers who opted in to receive newsletters.
According to customers targeted in this phishing campaign, they received fake “critical security alert” emails from help@trezor.io claiming that a “hardware microcontroller vulnerability” in Trezor cold storage wallets’ STM32 microcontrollers could expose their seeds to brute-force cracking.
The phishing emails tried to trick recipients into clicking a malicious link that prompted them to download an app that asked them to enter their wallet backup.
Trezor says that it took down the domain used in the phishing attacks within 20 minutes, disabling the link and limiting the campaign’s impact to 2,500 customers who had clicked it before it was taken down.
“On September 9, 2026, Brevo, the third-party marketing platform Trezor uses for newsletter campaigns, suffered a security incident affecting 120 Brevo accounts. An unauthorized actor gained access to Brevo’s system and used it to send emails from various customer accounts, including Trezor’s,” the company said.
“The incident affected our opt-in newsletter database, roughly 347,000 email addresses. These addresses might be potentially used for other phishing attacks in the future. No other Trezor system was touched. We have suspended the Brevo account to stop further email distribution.”
In January 2024, Trezor disclosed another data breach after its third-party support ticketing portal was hacked and attackers stole data (including names, usernames, and email addresses) from roughly 66,000 users.
Trezor also disclosed a data breach last month after threat actors hacked ShipMonk, its logistics and shipping provider, using a critical Metabase SQL injection zero-day vulnerability, and stole customers’ order data, including full names, shipping addresses, email addresses, and phone numbers.
While Trezor initially said the incident affected nearly 14,000 customers, a follow-up investigation found that the resulting breach affected an additional 67,000 U.S. customers, bringing the total to 81,000 individuals.
The company said that the incident also affected customers in Brazil, Colombia, Italy, Portugal, Sweden, and the United Kingdom who received orders between May 10 and August 8, 2026.
Since then, BleepingComputer also learned that ShipMonk received extortion emails from the ShinyHunters extortion gang following the breach.
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